Can you help me understand the movemement of tectonic plates and their margins

The Earth's surface is divide into plates, and these plates on the Crust move around slowly (mm's to cm's a year), this is due to convection currents in the mantle on which the crust sits. These convection currents are caused by radioactive decay in the Core, which produces heat. As the magma in the Mantle heats up, it becomes less dense than the magma around it and begins to rise from the bottom of the mantle to the top. Here the magma cools as it is now much further away from the core, as it cools it becomes less dense and begins to fall back towards the bottom of the mantle. The cycle of heating and cooling produces convection currents. Here as the magma cools, it creates frictional drag on the plate above it, slowly moving the plate.

Where these plates meet on the surface is called plate margins. There are three main types of plate margins; Destructive (Convergent), Constructive (Divergent) and conservative. Each margin has its own landforms and features. At destructive plate margins the plates converge (move together) due to convection currents in the mantle. When these plates meet the denser of the two plates is forced under the other and into the mantle. Here it is melted down and as the magma is hot and near the surface it forces its way back through the crust creating a volcano. Where the plate is subducting, pressure builds at what is known as the Benioff Zone. Here the less dense plate gets slowly dragged down, creating an ocean trench. At the point when maximum tension is reached the plate rebounds creating Rayleigh Waves also known as an Earthquake. At Constructive Margins, the plates diverge (move away) from one another creating an opening in the earths crust known as a fissure. Here the magma reaches the surface and runs out, slowly cooling creating a shallow sloping ridge, called an ocean ridge. If this occurs above ground this is known as a Rift Valley. The volcano produced is a Fissure Volcano, and earthquakes occur of a low magnitude as when the plates move apart it is a juddering rather than a smooth movement. Finally, Conservative Margins are where the plates move sideways past one another at different speeds. Here no crust is destroyed by subduction and no new crust is made. As these plates pass one another they build friction and tension spots build in a slip or stick situation. When enough pressure builds for one plate to unhook itself from the other a sharp judder occurs, creating an earthquake. Here however, no crust is destroyed and as such no volcanoes can form.

N.b. There is much more to this answer and itself is a whole topic covered by AQA and Edexcel and requires much more than what is written.